The prior art is already aware of various arrangements of crawler tractor track chain drive assemblies. The prior art includes arrangements wherein provision is made for attenuating or reducing the noise usually accompanying the drive engagement between the sprocket and the chain itself. That is, the sprocket and chain are made of metal, and when the sprocket engages the chain bushings or the like, there is creation of noise, and there is also an undesirable impact between the metal parts and this causes a certain wearing and loading between the contacting parts, such as the sprocket teeth and the chain bushings. The prior art has recognized this problem, and it has presented certain constructions which are intended to solve the problem, such as the arrangements shown in U.S. Pat. Nos. 3,887,244 and 3,897,980 wherein an elastomeric member is attached to the track chain for noise attenuation. Other prior art examples of the use of elastomeric members attached to track chains, but in this instance as mid-pitch drive members, are shown in U.S. Pat. Nos. 3,563,614 and 3,567,294 and 3,680,929. However, in this latter group of patents, the function of the elastomeric member is for the drive engagement between the sprocket and the chain, rather than having the elastomeric member provided for the sole purpose of noise attenuation. Also, in all of the aforesaid examples of prior art, the elastomeric member is secured to the track chain track plate, and bolts or screws are utilized to secure the elastomeric members to the track plates. With these arrangements, the usual and desired arrangement of permitting dirt to move out of the interior of the track chain is impeded if not completely hampered and eliminated. Also, where screws and bolts are required to pass through the track plate and the elastomeric member, special parts and special machinings are necessarily required to achieve that. Still further, where the prior art has the elastomeric member disposed intermediate the chain bushings, it hampers the removal of dirt from the chain, since the usual opening in the chain track plate is closed off by the elastomeric member and dirt can not pass out the opening.
Accordingly, the present invention provides an improvement upon the prior art, and, more specifically, it overcomes the aforementioned problems and deficiencies of the prior art.
Still further, the present invention provides a track chain assembly which minimizes the noise commonly generated by contact between the sprocket and the track chain, and the present invention does so by means of providing an elastomeric member directly between the track chain bushing and the track plate and with the member available for initial engagement by the sprocket teeth prior to the time that the sprocket teeth engage the track chain bushing.
Still further, the present invention provides a track chain assembly with the noise attenuating elastomeric member mentioned above, and with the entire arrangement being such that provision is still retained for the passage of dirt from the interior of the track chain and through the usual opening provided in the track plate, and the incorporated elastomeric member does not block the track plate opening and therefore does not impede the removal of dirt from the interior of the track chain.
Still further, the present invention provides a track chain assembly arranged with a noise attenuating elastomeric member which is secured to the track chain without the requirements of any bolts or screws, and which can be readily and easily replaced simply by removal of the track plate. Still further, the present invention provides an elastomeric member which serves to attenuate noise in the assembly of a track chain and sprocket drive, and the present invention provides the arrangement such that any presently existing or prior art assembly can accommodate the elastomeric member and arrangement of this invention, without requiring any special parts of machining or the like.
Still further, the present invention provides a crawler tractor track chain drive assembly which has an elastomeric member for attenuating noise and with the assembly also being arranged so that dirt can pass from the interior of the track chain itself, and the elastomeric member does not block or impede the passage of the dirt and therefore there is no change in the pitch between the sprocket and the chain which might otherwise occur due to tightening of the chain because of accumulation of dirt thereon.
Other objects and advantages will become apparent upon reading the following description in light of the accompanying drawings.